This study intends to find out the correlation between the cover depth and the bond characteristics of UHPC through pull-out tests of UHPC specimens with different cover depths and bond tests of rebar using flexural m...This study intends to find out the correlation between the cover depth and the bond characteristics of UHPC through pull-out tests of UHPC specimens with different cover depths and bond tests of rebar using flexural members. In this experimental study, specimens are fabricated with the lap-splice length as test variable in relation with the calculation of the lap-splice length for 180- MPa UHPC. Moreover, specimens are also fabricated with the cover depth as test variable to evaluate the effect of the cover depth on the UHPC flexural members. The load-displacement curves are analyzed for each of these test variables to compute the lap-splice length proposed in the K-UHPC structural design guideline and to evaluate the influence of the cover depth on the flexural members. As a result, the stability of the structural behavior can be significantly enhanced by increasing slightly the cover depth specification of the current UHPC Structure Design Guideline from the maximum value between 1.5 times of rebar diameter and 20 mm to the maximum value between 1.5 times of rebar diameter and 25 mm.展开更多
The thixotropic structural build-up is crucial in extrusion-based three-dimensional(3D)concrete printing.This paper uses a theoretical model to predict the evolution of static and dynamic yield stress for printed conc...The thixotropic structural build-up is crucial in extrusion-based three-dimensional(3D)concrete printing.This paper uses a theoretical model to predict the evolution of static and dynamic yield stress for printed concrete.The model employs a structural kinetics framework to create a time-independent constitutive link between shear stress and shear rate.The model considers flocculation,deflocculation,and chemical hydration to anticipate structural buildability.The reversible and irreversible contributions that occur throughout the build-up,breakdown,and hydration are defined based on the proposed structural parameters.Additionally,detailed parametric studies are conducted to evaluate the impact of model parameters.It is revealed that the proposed model is in good agreement with the experimental results,and it effectively characterizes the structural build-up of 3D printable concrete.展开更多
文摘This study intends to find out the correlation between the cover depth and the bond characteristics of UHPC through pull-out tests of UHPC specimens with different cover depths and bond tests of rebar using flexural members. In this experimental study, specimens are fabricated with the lap-splice length as test variable in relation with the calculation of the lap-splice length for 180- MPa UHPC. Moreover, specimens are also fabricated with the cover depth as test variable to evaluate the effect of the cover depth on the UHPC flexural members. The load-displacement curves are analyzed for each of these test variables to compute the lap-splice length proposed in the K-UHPC structural design guideline and to evaluate the influence of the cover depth on the flexural members. As a result, the stability of the structural behavior can be significantly enhanced by increasing slightly the cover depth specification of the current UHPC Structure Design Guideline from the maximum value between 1.5 times of rebar diameter and 20 mm to the maximum value between 1.5 times of rebar diameter and 25 mm.
基金A grant from CSIR,New Delhi,generously funds this studypartially supported by the City University of Hong Kong,China(No.9610661).
文摘The thixotropic structural build-up is crucial in extrusion-based three-dimensional(3D)concrete printing.This paper uses a theoretical model to predict the evolution of static and dynamic yield stress for printed concrete.The model employs a structural kinetics framework to create a time-independent constitutive link between shear stress and shear rate.The model considers flocculation,deflocculation,and chemical hydration to anticipate structural buildability.The reversible and irreversible contributions that occur throughout the build-up,breakdown,and hydration are defined based on the proposed structural parameters.Additionally,detailed parametric studies are conducted to evaluate the impact of model parameters.It is revealed that the proposed model is in good agreement with the experimental results,and it effectively characterizes the structural build-up of 3D printable concrete.
